Knife gate is one of the few application-specific designs among industrial valves. It basically features a design that ensures minimum contact between moving parts of the valve. This is achieved by having a gate that is practically held between layers of gland packing without touching the body parts during most of its travel.

The seating itself is accomplished with a non-sliding motion aided by jams located in the body. Avoiding sliding contact between gate and body permits this valve to handle abrasive particles present in the media much better than conventional designs.

Another feature is the bevelled bottom edge of the gate(from which it derives the 'knife' in its name) which allows positive closure of the gate even when solid particles settled at the bottom of the body.

In handling abrasive media, deflection cones are generally used in order to avoid direct impingement of the media on the seat surfaces; hard facing of body or seating parts is also sometimes used, this is made possible by either stelliting the seat or gate or by nitride coating of the entire body and gate.

Another feature is the purge connection which let in suitable fluids at pressures higher than line pressure to clean seating surfaces(body purges) and packing area (chest purges). This minimises abrasive wear and tear during vave opening and closure.

Knife gate valves are excellent hopper isolation valves with their ability to cut through flowing powders and close by dislodging any material in the seating area. This is also perhaps the only valve design which can tolerate differential thermal expansion of its parts without affecting its functions, thus making an ideal choice for handling high temperature media.

Knife gate valves are generally uni-directional valves; however, modified designs are also available to handle bi-directional shut-off requirements. VAAS offers a wide choice in designs and options in their knife gate valve range.

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